The invention relates to LED illumination, and more particularly to LED illumination of cold storage compartments, for example commercial freezer cabinets.
Large commercial freezer cabinets are used to show and store products in food markets and elsewhere. Usually the types of freezer cabinets found in supermarkets have transparent doors, and the products inside are illuminated. Currently, fluorescent lighting usually is used to illuminate these products. The fluorescent lamps are usually positioned at the door posts of the cabinets.
This type of illumination system has several drawbacks. For one thing, the light source is generally inside the freezer, and therefore it produces heat. This requires extra cooling power to compensate for heat production caused by lighting.
Another problem is that due to the low temperatures within the cabinets, efficiency of the fluorescent lamps decreases. For example, at an ambient temperature of 0xc2x0 Centigrade (C.), efficiency can be half of what it would be at an ambient temperature of 25xc2x0 C.
Also, starting the fluorescent lamps can be a problem that due to low temperatures. In order to avoid these problems, users of the cabinets often leave the freezer lighting on continually, even during hours when no one is likely to be looking into the cabinetsxe2x80x94for example when a store is closed for the evening. This wastes energy.
Another problem is that low temperatures negatively impact fluorescent tube gas discharge stability, resulting in flickering of the lamp.
Additionally, fluorescent lighting requires high-voltage inside the freezer, which could cause safety problems, particularly while cleaning the lamp.
Further, lifetime of fluorescent lamps is generally limited to 10,000 hours. If a single lamp in the freezer fails, immediate replacement is necessary.
Further, light distribution with fluorescent lighting is not optimal for providing even vertical illumination. Products nearer the lamps will be illuminated more brightly then products in between the lamps.
To address at least some of these problems, the present invention provides a storage compartment equipped with a light emitting diode (LED) light source for illuminating contents inside the compartment. The LED light source comprises an LED light engine outside the compartment and a light guide inside the compartment. The light is optically coupled to be LED light engine for bringing light illumination from the LED light engine into the compartment via the light guide.